Lubricant for thin film storage media

ABSTRACT

Embodiments relate to lubricants disposed over magnetic storage media, such as rotatable thin film magnetic discs. One embodiment comprises a lubricant compound of a fluoropolyether chain having one or more carbonyl-imide pairs. For example, the carbonyl-imide pair may be located at one end, both ends, and/or in the middle of the fluoropolyether chain.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 60/347,161, filed Jan. 9, 2002, which is herein incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to lubricants.More particularly, embodiments relate to lubricants disposed overmagnetic storage media, such as rotatable thin film magnetic discs.

2. Description of the Related Art

Information storage systems, such as disk drive memory systems, havebeen used in computers and other data processing devices for many yearsfor storage of digital information. Typically, information is recordedon concentric memory tracks of a rigid magnetic storage medium, such asa disc, the actual information being stored in the form of magnetictransitions within the medium. The disc is typically comprised of a thinrigid substrate, an underlayer, a magnetic layer, and a protectiveovercoat. The discs are rotatably mounted on a spindle, the informationbeing accessed by means of transducers located on a pivoting arm whichmoves radially over the surface of the disc. The read/write heads ortransducers must be accurately aligned with the storage tracks on thedisc to ensure proper reading and writing of information.

In the operation of typical disk drives, the read/write head slidesagainst the surface of the disc as the disc starts to rotate. Uponreaching a predetermined rotational speed, the head floats in air at apredetermined distance from the surface of the disc where the head ismaintained during reading and recording operations. The read/write headfloats very close to the surface of the disc during movement to maximizethe signal quality. Due to the spacing closeness, the head can makeintermittent contact with the disc surface. The head also slides on thedisc as the disc rotation stops.

To reduce the wear and material interaction on the surface of the disc,the disc further includes a lubricant topcoat typically applied over theprotective overcoat. The lubricant is intended to reduce the wear of theinterface between the read-write head and the disc, especially duringstart/stop cycles in which the head is in contact with the disc. Thelubricant system typically comprises a mixture of a perfluoropolyether,such as “FOMBLIN® Z-DOL” available from Ausimont USA, a subsidiary ofMontedison S.P.A. of Milan, Italy, and a catalytic blocking agent, suchas the hexaphenoxy compound “X-1P” available from The Dow ChemicalCompany of Midland, Mich. The perfluoropolyether provides lubrication ofthe disc while the catalytic blocking agent prevents catalyticdecomposition of the perfluoropolyether. It is believed that thecatalytic blocking agent prevents exposed metal sites of the head or ofthe disc from reacting with the perfluoropolyether.

One problem with the lubricant system including a mixture of a lubricantcompound, such as a perfluoropolyether, and a catalytic blocking agent,such as a hexaphenoxy compound, is that the catalytic blocking agent maybe immiscible with the lubricant compound and may form droplets of thecatalytic blocking agent on the lubricant compound. This “phaseseparation” between the lubricant compound and the catalytic blockingagent may cause reduced protection of the lubricant compound by thecatalytic blocking agent. Moreover, the droplets of the catalyticblocking agent at the surface of the disc may perturb the head duringoperation of the disk drive, thus, causing the head to improperly reador write to the disc.

Therefore, there is a continuing need for an improved lubricant systemto be used with magnetic storage media.

SUMMARY OF THE INVENTION

Embodiments relate to lubricants disposed over magnetic storage media,such as rotatable thin film magnetic discs. One embodiment comprises alubricant compound of a fluoropolyether chain having one or morecarbonyl-imide pairs. In one aspect, the carbonyl-imide pair may belocated at one end, both ends, and/or in the middle of thefluoropolyether chain. Another embodiment comprises a method ofmanufacturing a magnetic storage medium comprising forming a protectiveovercoat over a magnetic layer of the magnetic storage medium. Then, alubricant topcoat is applied over the protective overcoat. The lubricanttopcoat may comprise a fluoropolyether having one or more carbonyl-imidepairs. Still another embodiment comprises a magnetic storage mediumincluding a carbon-overcoated magnetic layer and a lubricant topcoatformed over the carbon-overcoated magnetic layer. The lubricant topcoatmay comprise a fluoropolyether having one or more carbonyl-imide pairs.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 is a simplified schematic top plan view of one exemplaryembodiment of an information storage system.

FIG. 2 is a schematic cross-sectional view of one exemplary embodimentof a magnetic storage medium.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a simplified schematic top plan view of one exemplaryembodiment of an information storage system 10. The information storagesystem 10 may include a sealed housing 12, a magnetic storage medium 14which is usually in the form of a disc or discs, a read/write head 16,and an actuator assembly 17. The actuator assembly 17 may include anactuator arm 18 for positioning the read/write head 16 disposed at theend of the actuator arm 18 over the surface of the storage medium 14.Multiple read/write heads may also be employed. The read/write head 16carries a read/write element, which can be any type of read/writeelement known in the art, such as inductive thin film, MIG or MR. Thestorage medium 14, such as a disc or discs, may be mounted to a spindlemotor 10 which spins the storage medium 14. The information storagesystem 10 may include a header assembly 22 to transfer electronicsignals to and from a motor 24 which positions the actuator and theread/write head 16 as data is transferred to and from the storage medium14. The information storage system 10 may be employed with a computer,printer or fax machine or other host system. Other embodiments of aninformation storage system may also be used.

FIG. 2 is a schematic cross-sectional view of one exemplary embodimentof a magnetic storage medium 102. The magnetic storage medium 102includes a substrate 104. The substrate 104 typically comprises analuminum (Al) alloy material, such as an aluminum-magnesium (Al—Mg)alloy, plated with an amorphous nickel-phosphorus layer. Alternatively,the substrate 104 may comprise other materials, such as glass,glass-ceramic, graphite materials, other materials, and combinationsthereof. The substrate 104 may be textured or untextured. An underlayer106, such as a chromium (Cr) or chromium alloy underlayer, may be formedover each side of the substrate 104. The underlayer 106 may be appliedas a composite comprising a plurality of sub-layers 106A. A magneticlayer 108, such as a cobalt alloy magnetic layer, may be formed over theunderlayer 106. A protective overcoat 110, such as a carbon overcoat,may be formed over the magnetic layer. The carbon overcoat may alsoincorporate other elements, such as hydrogen and/or nitrogen. Alubricant topcoat 112, such as a lubricant topcoat comprising thelubricant composition described in greater detail below, may be formedover the protective overcoat 110. The surface of the magnetic storagemedium 112 may be textured or untextured. Also, separate textured dataand landing zones may be provided on the surface of the disc. As shownin FIG. 2, the magnetic storage medium 112 includes thin film layersdeposited on each side of the substrate 104. In other embodiments, thinfilm layers may be deposited on one side of the substrate 104. Otherembodiments of a magnetic storage medium may also be used.

The lubricant composition, such as the lubricant composition of thelubricant topcoat in FIG. 2, includes a lubricant compound comprising afluoropolyether chain having at least one carbonyl-imide pair.Preferably, the carbonyl-imide pair is a carbonyl-imide pair in whichthe nitrogen of the imide group is linked to the alpha position carbonof the carbonyl group. One embodiment of the lubricant compoundcomprises a fluoropolyether chain having a carbonyl-imide pair at oneend of the fluoropolyether chain having the general structure of theformula:

Cl¹—FPE¹  (1)

in which Cl¹ represents a carbonyl-imide pair and FPE¹ represent afluoropolyether chain. Another embodiment of the lubricant compoundcomprises a fluoropolyether chain having a carbonyl-imide pair at bothends of the fluoropolyether chain having the general structure of theformula:

Cl²—FPE²-Cl³  (2)

in which Cl² and Cl³ each represents a carbonyl-imide pair, which may bethe same or different, but are preferably the same, and in which FPE²represent a fluoropolyether chain.

In regards to formula (1) and formula (2), Cl¹, Cl², and Cl³ may each beany carbonyl-imide pair, preferably any carbon-imide pair having thenitrogen of the imide group linked to the alpha position carbon of thecarbonyl group. Preferred embodiments of Cl¹, Cl², and Cl³ may eachcomprise a carbonyl-imide pair, having the nitrogen of the imide grouplinked to the alpha position carbon of the carbonyl group, representedby the general structure of the formula of R¹═N—(CR²R³)—(CO)—,R⁴═N—(NR⁵)—(CO)—, R⁶—N═(CR⁷)—(Co)—, or R⁸—N═N—(CO)— in which R¹ to R⁸are the same or different and may be an alkyl, alkenyl, alkoxy, aryl,aryloxy, arlyalkyl, arlyalkenyl, amine, imine, aromatic, or heterocyclic aromatic group. R¹ to R⁸ may be substituted or unsubstituted.Preferably, R¹ and R², R¹ and R³, R⁴ and R⁵, or R⁶ and R⁷ together withthe atoms binding them form a ring or rings system. More preferably, R¹and R², R¹ and R³, R⁴ and R⁵, or R⁶ and R⁷ together with the atomsbinding them form an aromatic ring or rings system.

Examples of preferred embodiments of the carbonyl-imide pairs of Cl¹,Cl², and/or Cl³ having the general structure of the formula ofR¹═N—(CR²R³)—(Co)—, R⁴═N—(NR⁵)—(CO)—, R⁶—N═(CR⁷)—(CO)—, R⁸—N═N—(CO)—include the following:

in which each R group may be the same or different and may be a hydrogenatom, halogen atom, alkyl, haloalkyl, alkenyl, haloalkenyl, alkoxy,haloalkoxy, aryl, haloaryl, arylalky, haloarylalky group, or otherpossible substituents.

In regards to formula (1) and formula (2), the fluoropolyether chain ofFPE¹ and FPE² may be any fluoropolyether chain. In general, thefluoropolyether chain of FPE¹ and FPE² each comprise a chain having amiddle section comprising perfluoroether units and end sectionscomprising any functional group. For example, FPE¹ and FPE² may each berepresented by the general structure having the formula—R¹¹—(OR¹²)_(w)—(OR¹³)_(x)—(OR¹⁴)_(y)—O—R¹⁵, in which R¹², R¹³, R¹⁴, arethe same or different and may be a fluoroalkyl or perfluoroalkyl group,preferably a C₁₋₄ fluoroalkyl or perfluoroalkyl group. W may be between1 and 500. X and Y are the same or different and may be between 0 and500. R¹¹ comprises any functional group, such as one or moreperfluoroether units, one or more partially fluorinated ether units, oneor more non-fluorinated ether units, one or more hydroxy units, one ormore fluoroalkyl units, one or more fluoroalkenyl units, other suitablefunctional groups, and combinations thereof. For FPE¹, R¹⁵ may be ahydrogen, carboxylate, alkyl, haloalkyl, aryl, haloaryl, arylalky,haloarylalky, or piperonyl group. For FPE², R¹⁵ comprises any functionalgroup, such as one or more perfluoroether units, one or more partiallyfluorinated ether units, one or more non-fluorinated ether units, one ormore hydroxy units, one or more fluoroalkyl units, one or morefluoroalkenyl units, other suitable functional groups combinationsthereof. Examples of preferred embodiments of the fluoropolyether chainof FPE¹ and FPE² include a fluoropolyether chain having one or more ofthe following groups: (—O—CF₂)_(n); (—O—CF₂—CF₂)_(n);(—O—CF₂—CF₂—CF₂)_(n); (—O—CF₂—CF(CF₃))_(n). For FPE¹, suchfluoropolyether chains preferably include:

—OCH₂CF₂—(O—CF₂)_(p)—(O—CF₂—CF₂)_(q)—OCF₂CH₂—OH; and

—OCH₂CF₂—(O—CF₂—CF₂)_(q)—(O—CF₂)_(p)—OCF₂CH₂—OH;

in which Q and P may be the same or different and may be between 1 and500. For FPE², such fluoropolyether chains preferably include:

—OCH₂CF₂—(O—CF₂)_(p)—(O—CF₂—CF₂)_(q)—OCF₂CH₂—O—;

in which Q and P may be the same or different and may be between 1 and500. Other fluoropolyethers which may be used for FPE¹ and FPE², includethe following and their derivatives thereof:

—(O—CF₂)_(p)—(O—CF₂—CF₂—)_(q)—O—CF₃;

—(O—CF₂—CF₂)_(q)—(O—CF₂)_(p)—O—CF₃;

—(O—CF₂)_(p)—(O—CF₂—CF(CF₃))_(q)—O—CF₃;

—(O—CF₂—CF(CF₃))_(q)—(O—CF₂)_(p)—O—CF₃;

—(O—CF₂—CF₂—CF₂)_(p)—O—CF₂—CF₃;

—(O—CF₂—CF₂—CF₂)_(p)—O—CF₂—CF₂—CF₃;

—(O—CF₂—CF(CF₃))_(q)—O—CF₂—CF₃;

—(O)—(CF(CF₃)—CF—O)_(q)—CF₂—CF₂—CF₃;

in which Q and P may be the same or different and may be between 1 and500.

Preferred embodiments of the lubricant compound comprise afluoropolyether chain having the carbonyl-imide pair at both ends of afluoropolyether chain of formula (2). A particularly preferredembodiment of the lubricant compound comprises the compound termed“Pi-Z” of the general structure:

in which P and Q may be the same or different, but are preferably thesame, and may be between 1 and 500. Another particularly preferredembodiment of the lubricant compound comprises the compound termed“Py-Z” of the general structure:

in which P and Q may be the same or different, but are preferably thesame, and may be between 1 and 500.

Another embodiment of the present lubricant compound comprises afluoropolyether chain having a carbonyl-imide pair at the middle of thefluoropolyether chain having the general structure of the formula:

FPE³-Cl⁴—FPE⁴  (3)

in which Cl⁴ represents a carbonyl-imide pair and FPE³ and FPE⁴represent a fluoropolyether chain, which may be the same or different,but are preferably the same.

In regards to formula (3), Cl⁴ may be any carbonyl-imide pair,preferably any carbon-imide pair having the nitrogen of the imide grouplinked to the alpha position carbon of the carbonyl group. Preferredembodiments of Cl⁴ comprise a carbonyl-imide pair, having the nitrogenof the imide group linked to the alpha position carbon of the carbonylgroup, represented by the general structure of the formula of—(C═O)—R²¹═N—R²²—(C═O)—, in which R²¹ and R²² are the same or differentand may be an alkyl, alkenyl, alkoxy, aryl, aryloxy, arlyalkyl,arlyalkenyl, amine, imine, aromatic, or hetero cyclic aromatic group.R²¹ and R²² may be substituted or unsubstituted. Preferably, R²¹ and R²²together with the atoms binding them form a ring or rings system. Morepreferably, R²¹ and R²² together with the atoms binding them form anaromatic ring or rings system.

An example of a preferred embodiment of a carbonyl-imide pair of Cl⁴having the general structure of the formula of —(C═O)—R²¹═N—R²²—(C═O)—include the following:

in which each R group may be the same or different and may be a hydrogenatom, halogen atom, alkyl, haloalkyl, alkenyl, haloalkenyl, alkoxy,haloalkoxy, aryl, haloaryl, arylalky, or haloarylalky group.

In regards to formula (3), the fluoropolyether chain of FPE³ and FPE⁴may be any fluoropolyether chain. In general, the fluoropolyether chainof FPE³ and FPE⁴ each comprise a chain having a middle sectioncomprising perfluoropolyether units and end sections comprising anyfunctional group. For example, FPE³ and FPE⁴ may each be represented bygeneral structure of the formula—R³¹—(OR³²)—(OR³³)_(x)—(OR³⁴)_(y)—O—R³⁵, in which R³², R³³, R³⁴, aredifferent and may be a fluoroalkyl or perfluoroalkyl groups, preferablya C₁₋₄ fluoroalkyl or perfluoroalkyl group. W may be between 1 and 500.X and Y are the same or different and may be between 0 and 500. R³¹comprises any functional group, such as one or more perfluoroetherunits, one or more partially fluorinated ether units, one or morenon-fluorinated ether units, one or more hydroxy units, one or morefluoroalkyl units, one or more fluoroalkenyl units, other suitablefunctional groups, or combinations thereof. R³⁵ may be a hydrogen,carboxylate, alkyl, haloalkyl, aryl, haloaryl, arylalky, haloarylalky,or piperonyl group. Examples of preferred embodiments of thefluoropolyether chain of FPE³ and FPE⁴ include a fluoropolyether chainhaving one or more of the following groups: (—O—CF₂)_(n);(—O—CF₂—CF₂)_(n); (—O—CF₂—CF₂—CF₂)_(n); (—O—CF₂—CF(CF₃))_(n). Suchfluoropolyether chains preferably include:

—OCH₂CF₂—(O—CF₂)_(p)—(O—CF₂—CF₂)_(q)—OCF₂CH₂—OH; and

—OCH₂CF₂—(O—CF₂—CF₂)_(q)—(O—CF₂)_(p)—OCF₂CH₂—OH;

in which Q and P may be the same or different and may be between 1 and500. Other fluoropolyethers which may be used for FPE³ and FPE⁴, includethe following and their derivatives thereof:

—(O—CF₂)_(p)—(O—CF₂—CF₂—)_(q)—O—CF₃;

—(O—CF₂—CF₂)_(q)—(O—CF₂)_(p)—O—CF₃;

—(O—CF₂)_(p)—(O—CF₂—CF(CF₃))_(q)—O—CF₃;

—(O—CF₂—CF(CF₃))_(q)—(O—CF₂)_(p)—O—CF₃;

—(O—CF₂—CF₂—CF₂)_(p)—O—CF₂—CF₃;

—(O—CF₂—CF₂—CF₂)P—O—CF₂—CF₂—CF₃;

—(O—CF₂—CF(CF₃))_(q)—O—CF₂—CF₃;

—(O)—(CF(CF₃)—CF—O)_(q)—CF₂—CF₂—CF₃;

in which Q and P may be the same or different and may be between 1 and500. A particularly preferred embodiment of the lubricant compoundcomprises the compound termed “Pi-2Z” of the general structure:

in which P and Q may be the same or different, but are preferably thesame.

Other embodiments of the present lubricant compound are possible such asa fluoropolyether chain having a plurality of carbonyl-imide pairs. Forexample, the lubricant compound may comprise the general structure ofthe formula: Cl—FPE-Cl—FPE-Cl; Cl—FPE-Cl—FPE-Cl—FPE-Cl; and otherpossible structures. Embodiments of the present invention includefluoropolyether homopolymers, copolymers, random polymers, and blockpolymers. Different repeat units may be randomly distributed along thebackbone of the fluoropolyether or distributed as a block of one type ofrepeat unit and subsequent blocks of different repeat units along thebackbone of the fluoropolyether. The fluoropolyether can be completelyfluorinated or partially fluorinated and can be linear or branched.

One example of the synthesis process for preparing Pi-Z comprises thefollowing general equation:

The process comprises dissolving “Zdeal” (10 g, 5 mmol), available fromAusimont, in a hydrofluorocarbon “Vertrel XF” (20 mL) available fromDuPont Fluoroproducts, a division of E. I. du Pont de Nemours andCompany of Wilmington, Del. Then, 2-pyridinecarboxylic chloride (1.56 g,11 mmol) and 4-dimethylaminopyridine (0.1 g) in dichloromethane (10 mL)were added to the solution. Triethylamine was added in drop-wisely tothe solution as an acid acceptor, and the mixture was allowed to reactat room temperature for 4 hours. The solution was poured into Vertrel XF(100 mL) after it was cooled, and washed with a dilute HCl aqueoussolution. A evaporation step followed by and a supercritical fluidextraction purification step provided a clear liquid product of Pi-Zfluoropolyether (8.5 g, 85%). The product was identified by UV spectra.Other synthesis processes for preparing Pi-Z are also possible.

One example of the synthesis process for preparing Py-Z comprises thefollowing general equation:

The process comprises dissolving Zdeal (10 g, 5 mmol) in ahydrofluorocarbon Vertrel XF (20 mL). Then, 3,5-dimethylpyrazole (1.44g, 15 mmol) in methanol (10 mL) was added to the solution and themixture was refluxed for 24 hours. The solution was poured into VertrelXF (100 mL) after it was cooled, and washed with a dilute HCl aqueoussolution. A evaporation step followed by a supercritical fluidextraction purification step gave of a clear liquid product of Py-Zfluoropolyether (8 g, 80%). The product was identified by UV spectra.Other synthesis processes for preparing PyZ are also possible.

The present lubricant compounds, whether of formula (1), formula (2), orformula (3), preferably have an average molecular weight (M_(n)) ofbetween about 2,000 Daltons and about 6,000 Daltons. The lubricantcomposition may be unfractionated. Alternatively, the lubricantcomposition may be fractioned. For example, the lubricant compositionmay be fractionated to remove certain molecular weight lubricantcompounds. Not wishing to be bound by theory, it is believed thatremoving low molecular weight lubricant compounds provides a lubricantcomposition with improved stiction and wear properties at a very lowtopcoat thickness. The lubricant composition may be prepared byfractionating starting materials of fluoropolyethers or the end-productmay be fractionated. Fractionating can be achieved by distillation,solvent extraction, chromatography, e.g. (HPLC), or other molecularweight separation techniques.

The lubricant composition may be applied over magnetic media by anytechnique known in the art, such as dip, vapor, spray, solvent,solvent-free, vacuum, and non-vacuum processes. The lubricantcomposition may be applied as one layer or as multiple layers. Toprovide desirable lubricating properties, the lubricant composition ispreferably applied to a thickness between about 10 angstroms and about30 angstroms. Thicknesses of less than 10 angstroms and greater than 30angstroms of the lubricant composition may also be used. In addition,after application, a post-treatment of the lubricant topcoat may beperformed, such as a heat, IR, UV, plasma, gas treatment, or othertreatment known in the art.

Not wishing to be bound by theory, it is believed that the presentlubricant compounds provide good lubrication properties, such as lowstiction and friction properties while also being resistant to catalyticattack. The present lubricant compound incorporates the functional groupof a catalytic blocking agent into the fluoropolyether chain. Therefore,it is believed that the present lubricant composition does not havephase separation problems of other lubricant mixture systems. Inaddition, since a separate catalytic blocking agent compound does notneed to be provided in the lubricant system, the application process ofthe lubricant composition is simplified.

EXAMPLE

The following tests demonstrate the capabilities of the presentinvention and such examples are offered by way of illustration and notby way of limitation.

Example 1

Thermogravimetric analysis (TGA) tests were performed on samplescomprising various lubricant systems. A first sample comprised alubricant system of the mixture of FOMBLIN® Z-DOL with Irganox MD 1024(available from Ciba-Geigy). A first comparative sample comprised alubricant system of FOMBLIN® Z-DOL. Thermogravimetric analysis spectrashowed that the first sample had a lower mass loss rate over temperaturein comparison to the comparative sample. Not wishing to be bound bytheory, it is believed that the TGA spectra showed that the Irganox MD1024 of the first sample is capable of inhibiting catalyticdecomposition of FOMBLIN® Z-DOL. It is further believed that thecarbonyl-imide functional group, in which the nitrogen of the imidegroup is linked to the alpha position carbon of the carbonyl group, ofthe Irganox MD 1024 acts in blocking metal catalytic sites andincorporating this functional group into a fluoropolyether chainprovides protection against catalytic attack.

Example 2

Potentiostatic corrosion tests were performed on samples comprising asubstrate having a carbon overcoat with various lubricants formedthereover. A second sample comprised a substrate lubed with Pi-Z. Athird sample comprised a substrate lubed with Pi-2Z. A secondcomparative sample comprised a substrate lubed with the mixture ofFOMBLIN® Z-DOL and X1P. Each sample was immersed into a sodium chloridesolution and was biased at a 900 mV potential for 10 minutes. The totalamount of charge (“total corrosion charge”) passing through each systemover this 10 minutes period of time was measured and calculated. Thetotal corrosion charge of the second sample and the third sample wasless than the total corrosion charge of the second comparative sample.Therefore, the second sample and the third sample showed betterpotentiostatic corrosion resistance than the second comparative sample.Not wishing to be bound by theory, it is believed that thepotentiostatic corrosion resistance data shows that the second sampleand third sample is resistance to decomposition.

Example 3

Contact start-stop (CSS) tests were performed on samples comprising adisc having a carbon overcoat with various lubricants formed thereover.A fourth sample comprised a disc lubed with Pi-Z. A fifth samplecomprised a disc lubed with Pi-2Z. A third comparative sample compriseda disc lubed with a mixture of FOMBLIN® Z-DOL and X1P.

Contact start-stop tests were performed in a conventional spin standusing 10,000 start/stop cycles in which the discs were spun to a speedof 7,200 rpm. Stiction and friction data were obtained at ambienttemperature and ambient humidity. None of the samples “crashed.” Thefourth sample and the fifth sample showed low stiction and low frictionvalues similar to the low stiction and low friction valves of thecomparative sample. Not wishing to be bound by theory, it is believedthat the CSS data shows that the fourth sample and the fifth sampleprovide good lubrication properties.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1-16. (canceled)
 17. A magnetic storage medium, comprising: acarbon-overcoated magnetic disc; and a lubricant means for blockingcatalytic metal sites, the lubricant means formed over thecarbon-overcoated magnetic disc.
 18. The magnetic storage medium ofclaim 17, wherein the lubricant means comprises a composition of asingle class of compounds.
 19. The magnetic storage medium of claim 17,wherein the lubricant means comprises a lubricating polymer backbone anda catalytic blocking functional group incorporated into the polymerbackbone.
 20. The magnetic storage medium of claim 17, wherein thelubricant means is in a single phase.